Automatic tuyere punching apparatus



Dec. 14, 1954 B. T. BERGE 2,696,979

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Filed April 16, 1951 Dec. 14, 1954 a. T. BERGE 2,696,979

AUTOMATIC TUYERE PUNCHING APPARATUS 7 Sheets-Sheet 6 Filed April 16 1951ya me 97 99 #6 12 24 INVENTOR.

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United States Patent AUTOMATIC TUYERE PUNCHING APPARATUS Byron T. Berge,McGill, Nev., assignor to Kennecott Copper Corporation, New York, N. Y.,a corporation of New York Application April 16, 1951, Serial No. 221,253

11 Claims. (Cl. 266-42) This invention relates to apparatus formechanically punching the tuyeres of converters, and more particularlyto automatically controlled fluid pressure operated apparatus forcleaning such tuyeres to remove encrustations or obstructions that areformed at the inner ends -of the tuyeres during blowing periods in whichair is introduced through the tuyeres into the molten material undertreatment in the converter.

Examples of fluid operated mechanical tuyere punching apparatus areshown in Larson and Berge Patent No. 2,432,996, issued December 23,1947, and reference is made thereto for a further description of theoperation of converters such as those used in the production of blistercopper, and the necessity for frequent punching of the tuyeres to removethe obstructions and thereby maintain a satisfactory rate ofintroduction of blowing air. As brought out in said patent, it isadvantageous to provide a separate complete punching unit mounted on theconverter adjacent each tuyere and provided with motor means foreffecting a rapid reciprocation of a punch rod within the tuyere, tomove the tip of the punch rod rapidly inward past the zone ofobstruction at the inner end of the tuyere and to then quickly reversethe movement and move the punch rod tip outwardly past the obstructionzone to a normal rest position within the tuyre.

Reference is also made to an application of Larson and Berge Ser. No.109,084, filed August 8, 1949, now Patent No. 2,619,938, granted Dec. 2,1952 which discloses a particularly advantageous type of fluid pressureoperated motor for use in such a converter punching unit, in which aninward or forward stroke of the punch rod is effected by supply ofmotive fluid under pressure at the rearward side of a piston connectedto the punch rod, and in which air is trapped and compressed forwardlyofthe piston during the forward stroke and is utilized to effect a rapidreversal and return stroke of the piston and punch rod.

In the forms of apparatus shown in the above mentioned patents, theoperation of each punching unit to effect rapid reciprocatory movementof its punch rod is initiated by manual control means at such intervalsas considered necessary in order to maintain a satisfactory rate ofintroduction of blowing air. The blowing air is normally supplied undersuitable pressure through a manifold or bustle pipe having separatebranch connections to the individual tuyeres, so that any excessiveobstruction formed at the inner end of one or more individual tuyerescauses a material reduction in the rate of inflow of air through suchtuyere or tuyeres. For optimum operation, it is desirable to maintain arelatively uniform high rate of introduction of air through all thetuyeres. More particularly, it is desirable to clean each individualtuyere promptly whenever it becomes so obstructed as to reduce the airflow therethrough below a certain minimum rate, and the principal objectof this invention is to provide an automatically controlled apparatusfor accomplishing this desirable result.

It accordingly becomes a particular object of this invention to providea punching apparatus for a converter having a plurality of tuyeres thatautomatically cleans a tuyre when the rate of flow of blowing air tothat particular tuyere falls below a certain predetermined value,independently of conditions at other tuyeres.

A further object of the invention is to provide an automatic tuyerepunching unit having a reciprocaoly operated punch rod and a novel andadvantageous control device 7 2,696,979 Patented Dec. 14, 1954responsive to variations in rate of flow of air and operable to initiateoperation of the punching unit to cause rapid reciprocation of punch,rod.

It is another object of the invention to provide an advantageous designof an automatic control device for a fluid motor that initiates actionof the fluid motor in {esponse to a pressure differential created in anair supply These and other objects of my invention have been attained ina converter having a plurality of tuyeres and a plurality of separatebranch air supply lines for blowing air, one branch line leading to eachof the tuyeres, by providing a plurality of separate and individualpunching units which are mounted on the converter with one unit on andassociated with each tuyere. Each punching unit has a punch rod which isconnected to the motor for reciprocation of the rod within the tuyere.An automatic control device is mounted upon each of the punching unitsand includes means responsive to variations in the rate of flow of theblowing air in the branch supply line leading to the associated tuyere.When actuated by a change in the rate of air flow, the automatic controldevice initiates operation of the fluid motor attached to thatparticular tuyre.

The automatic control device is itself novel and is adapted to effectinitial movement of the motor valve from an exhaust to an admissionposition. To do this, the control device is provided with a valveshifting member, which is typically and preferably a differential pistonsubiected at opposite sides to fluid pressure. At one side the fluidpressure is relativelv constant and is preferably the fluid pressure ofthe working fluid for the motor. The pressure at the other side of thevalve shiftin member is varied in order to obtain movement of the valveshifting member. Such variation is obtained by ope ing an exhaust valve,thus connecting one side of the difl erential piston with the atmosphereand causing movement toward that one side. The exhaust valve is actuatedbv pressure responsive valve operating means which responds to adifferential in pressure created in the air supply line to the tuyere bysuitable flow metering means. Such flow metering means is typically aVenturi tube, but other suitable means may be employed. The reducedpressure at the Venturi throat as compared with the static pressure ofthe air at a point upstream from the Venturi throat establishes adifferential pressure which bears a known relation to the rate of flowthrough the Venturi tube. When the quantity of air. per unit timeflowing through the tuyere drops below the quantity deemed satisfactoryfor converter operation, this pressure differential at the Venturi tubelikewise drops below a value which can be predetermined; and thisdecreased pressure differential in turn acts upon the pressureresponsive means for operating the exhaust valve.

Separate means are provided for returning the motor valve from theadmission to exhaust position. this valve return means being operated byfluid trapped ahead of the working piston. After return of the motorvalve, the exhaust valve of the automatic control device is closed andpressure is again built up at both sides of the differential piston sothat the unit is again restored to a condition in which it is ready foroperation.

'Other objects, not specifically mentioned, will be brought outhereinafter or will be apparent from the following description of apreferred embodiment of my invention, with reference to the accompanyingdrawings,

in which:

. Fig l is a rear end elevation of a plurality of automatic punchingunits mounted on a converter adjacent a plurality of tuyeres, showing aportion of the side of the converter;

Fig. 2 is a side elevation of one of the punching units mounted on theconverter, showing means including an adapter housing for mounting theunit on the converter and the connections for supplying air underpressure to the tuyere and to the punching unit and its automaticcontrol means;

Fig. 3 is a fragmentary combined elevation and sectional view on line 33in Fig. 2, showing a clamp for securing the adapter housing to theconverter;

Fig. 4 is a longitudinal median section of a punching unitincluding itsautomatic control means, and the adjacent tuyere and mounting means,with the punch rod in the retracted or rest position within the tuyere,and with certain parts shown in elevation;

Fig. 5 is an enlarged transverse vertical section on line 55 in Fig. 4;

Fig. 6 is an enlarged longitudinal median section of the punching unit,similar to Fig. 4, with most parts in the same positions as in Fig. 4;

Fig. 7 is a view similar to Fig. 6 but showing the parts in thepositions occupied when the punch rod actuating piston is moved to aposition near the forward end of its working stroke;

Figs. 8 and 9 are transverse vertical sectional views on lines 8-8 and9-9 respectively in Fig. 6;

Fig. 10 is a fragmentary longitudinal median section showing the exhaustvalve and related parts in the same positions as in Fig. 7, but on astill larger scale;

Fig; 11 is an enlarged transverse vertical section on line 11-11 in Fig.6;

Fig. 12 is a fragmentary horizontal section on line 12-12 in Fig. 6;

Fig. 13 is an enlarged partial transverse section on line 1313 in Fig.6; and

Fig. 14 is a fragmentary vertical section on line14-14 in Fig. 6.

Figs. 1, 2 and 4 show a portion of a copper converter A having aplurality of longitudinally spaced tuyeres B arranged in a row along oneside thereof. The converter comprises a cylindrical metal shell 1 and arefractory lining 2, and is constructed and mounted for rotation aboutits longitudinal axis in the conventional manner as shown argd describedmore fully in Patent 2,432,996 mentioned a ove.

Each tuyere B comprises a pipe or tube 3 extending through alignedopenings in the converter shell and the refractory lining into theinterior of the converter. The tuyere is a means for introducing blowingair through the walls of the shell and the lining into the body ofmolten material within the converter.

At the outer end of each tuyere B there is an adapter 4 connected to theouter end of tuyere pipe 3 and secured in place on the converter shellby means of clamp 7 and bolt 8. (See Figs. 2 and 3.) Clamp 7 has a pairof upwardly extending arms 9 which at their upper ends are recessed toengage lugs 11 on the adapter housing, while the lower end of clamp 7rests against a portion of shell 1. The ends of the clamp are held inengagement with their respective opposing members by tightening down thenut on bolt 8 which passes through the intermediate portion of clamp 7.Adjacent lugs 11 adapter 4 is provided with a convex spherically curvedsurface portion 12 which is held firmly against a similarly shapedconcave seat member 13 by the thrust of clamp 7. The thrust of theadapter holds seat member 13 against the external face of the convertershell.

Adapter 4 has an internal chamber 6 which communicates with the outerend of pipe 3 and forms a part of the passage supplying blowing air tothe tuyere pipe. Also connected to adapter 4 and communicating withinternal passage 6 is a branch supply line 14 for blowing air. As may beseen from Fig. 1, there are a plurality of tuyres, each with its ownpunching unit and each provided with its own branch air supply line 14,all of lines 14 communicating at their upper ends with a common manifoldor bustle pipe C which extends longitu dinally of the converter.

As shown in Figs. 1 and 4, adapter 4 also serves as a means for mountingin place on a tuyere the punching unit provided for each individualtuyere. Each of these punching units consists generally of a fluidpressure actuated motor F attached to one end of punch rod 15 foreffecting rapid reciprocation of the punch rod within pipe 3, asindicated particularly in Fig. 4. Each fluid motor F is provided with anautomatic control device indicated generally at G, the control devicebeing mounted directly upon the housing of fluid motor F of the punchingunit with which the control device is associated. As will be explainedlater in greater detail, the automatic control device includes meansresponsive to variations in the rate of flow of blowing air to thetuyere and operates to initiate action by the associated fluid motor tocause the punch rod 15 within the tuyere to reciprocate and clean outany obstruction which causes air to flow through the pipe at a ratebelow a predetermined value.

Compressed air, or other suitable elastic fluid, for operating the fluidmotor is supplied individually to each automatic control device andpunching unit through branch supply line 16; and as may be seen fromFig. l the individual branch lines 16 are connected at their upper endsto a common high pressure manifold 17 which ex' tends longitudinally ofthe converter.

Referring particularly now to Figs. 4 and 6, it will be seen that fluidmotor F comprises cylinder 20 suitably mounted in and between rearcylinder head casting 21 and front cylinder head casting 22. The termsfront and rear or other directional terms are used with reference to theworking stroke of piston 26 as being in a forward direction, such strokebeing from left to right in Fig. 6. The two head castings 21 and 22 aredrawn together by a plurality of tie bolts 24, shown in Fig. 2. A fluidtight connection between the walls of cylinder 20 and the surroundingwalls of the cylinder-receiving sockets in the two head castings, isobtained by the use of packing means at 25, such as an O-ring type orother suitable type of packing, adapted to hold the relatively highpressures reached in operation of the fluid motor. Within cylinder 20 isworking piston 26 which reciprocates within the cylinder and hasattached to it piston rod 27 which projects out of the cylinder throughan opening in front cylinder head 22. The front cylinder head isprovided at 28 with suitable packing, such as an O-ring type seal,adapted to prevent the escape of working fluid under pressure aroundpiston rod 27. At and 28, as well as at numerous other locations,O-rings have been indicated as a preferred means but without necessarylimitation to any particular means for holding fluid presures. Anysuitable kind of fluid packing may be used at the indicated or otherlocations as may be required.

Piston rod 27 also extends through and is slidably received in sleeve orgland 30 which supports and guides the piston rod during itsreciprocatory movement. Gland 30 is provided with lubrication means inthe form of packing at 31 which is provided with a suitable lubricantfor the piston rod. Additional lubricant may be supplied to 31 by asuitable conventional type of lubrication fitting, not shown in thedrawing.

In order to receive fluid motor F and its automatic control device G formounting upon the tuyere, adapter 4 is provided at its rear side withcover plate 32. Plate 32 has an opening through which gland 30 extendsand also holds between it and the rear face of adapter 4 an aperturedball seat plate 33. Gland 30 extends through the opening in ball seatplate 33, as shown in Figs. 4 and 6. The forward end of piston rod 27extends beyond gland 30 even when piston 26 is in the rear or restposition of Fig. 4. Thus the forward end of piston rod 27 passes throughthe internal air passage 6 of adapter 4 and is connected to punch rod15, the piston rod and punch rod being coaxial of tuyere pipe 3.

In order to prevent the escape of blowing air through adapter coverplate 32 when the fluid motor and its piston rod are removed, adapter 4is provided with ball check valve 34 which is located inside the adapterinchamber 6. When the piston rod and punch rod are removed from thetuyere, ball 34 falls down by gravity against the central opening inball seat plate 33 and closes the opening therein to prevent the escapeof air. When it is desired to mount the fluid motor in place, the punchrod is inserted in the opening in seat member 33 and when forced aheadmoves the ball check out of the way. The movement of the valve ball isguided by a pair of curved guides 35 inside the adapter. In the drawingsthe ball valve is shown only in the raised position which it occupieswhen the fluid motor is in place and the punch rod is in the tuyere.

Within rear cylinder head casting 21 and at a position near the rear endof cylinder 24), there is located pressure chest or supply chamber 37.Working fluid under pressure is supplied to chamber 37 through supplyline 16 which is connected to communicate directly with supply chamber37. Near the rear end of cylinder 20, but preferably spaced 2. shortdistance therefrom, is port 38 which serves not only as a means foradmitting working fluid to the rear end of the cylinder behind piston 26but also as a means for exhausting fluid from that end of the cylinder.As may be seen particularly well from Fig. 7,

lportJgS communicates between cylinder and supply chamer The flow ofworking fluid from the supply chamber to the cylinder through port 38 isregulated by means of a reciprocable valve assembly that includes slidevalve 40 which is within the supply chamber and is movable betweentheadmission position of Fig. 7 and the exhaust position of Fig. 6. Whenmoved forward as'shown in Fig. 7, valve 40 uncoversport 38 and allowsdirect flow of working fluid from the pressure chest into the workingcylinder of the fluid motor F. When the valve is moved to the rear, port38 is closed to chamber 37 and is placed in communication with port 41which communicates with the atmosphere thus allowing working fluid inthe cylinder to escape through port 38 and the space underneath valve 40into port 41 and thence to the atmosphere. Adjustable bafile plate 39 isslidably mounted on rear cylinder head casting 21 in position to more orless restrict port 41. and regulate the rate at which fluid exhauststhrough it. Valve 40 is held against rotation within chamber .37, whichis here shown as being circular in f ross-section, by a pair of lateralguides 42, shown in Valve 40 is shifted between the'two operatingpositions by means of spool 43 which engages the valve and is connectedto valve shifting rod 44. Valve rod 44 extends parallel to piston rod27. Rod 44 and spool 43,- together with the valve member 40 areconsidered as constituting the valve assembly of the fluid motor forcontrolling admission of working fluid to the motor cylinder. The rearend of supply chamber 37 is provided with a buffer assembly 45 includinga resilient member 45a. Thebuffer assembly limits the rearward travel ofthe valve assembly to properly locate valve member 40 in the exhaustpositron and also absorbs in member 4511 the shock of stopping the valveassembly as it shifts to the rear. The reasons for a sudden reversal anda rapid retraction of the punch rod after a forward punching stroke areset forth 1n greater detail in Patent 2,432,996 referred to above. sirable that pressure actuated valve return means be provided forautomatically and positively shifting the valve to exhaust position at apredetermined point in the forward stroke'of punch rod 15. This valvereturn means compr 1ses aux1l1ary piston 47 mounted for reciprocation incylindrical bore 48 which is located in the upper portron of frontcylinder head 22. The rear end of piston 47 has attached to it pistonrod 49which is guided in retamer plate 50 that closes the rear end ofcylinder 48 and the forward end of cylinder 58. Piston rod 49 is mountedcoaxially with valve rod 44 and the opposed ends of these i wo godsare'adapted to engage each other, as shown in The front end of cylinder48 ahead of piston 47 is in free communication with the front end ofcylinder 20 ahead of piston 26 through passageway 52 so that air trapped1n the working cylinder ahead of the piston is utilized to actuateauxiliary piston 47, as will be later described more fully. At the rearside of piston 47, cylinder 48 is placed in communication with the,atmosphere by means of passage 53, thus preventing fluid pressure frombuilding up on the back side of piston 47. Piston 47 is provided with anO-ring or other suitable sealing means in order to effect a fluid-tightseal between the p ston and the cylinder walls, and the same is alsoprovided for piston rod 49 in retainerplate' 50. It will be noted thatthe forward end of piston 47 is provided with a forwardly extendingprojection so that when the piston In order to accomplish this motion,it is deential bore in cylinder-block 56. The differential bore is intwo parts of different diameters; One part is cylinder 57 of relativelysmaller diameter which opens at one end to supply chamber 37; the otherpart is cylinder 58 of relatively larger diameter which is closed at itsforward end by retainer plate 50. The walls of the differential boreconstrain differential piston 55 to linear movement parallel to valverod 44, which extends through the differential piston, and parallel tothe movement of valve 40. It will be seen that with this arrangement theend of piston 55 of smaller diameter is subjected to the substantiallyconstant fluid pressure existing in supply chamber 37 while the other oropposite side of the piston is subjected to the variable fluid pressureexisting in cylinder 58; Cylinders 57 and 58 are in communication witheach other through passage 59 which extends longitudinally of thedifferential piston, the rate of flow of fluid through the passage beingclosely regulated by-means of orifice screw 60 screwed into the frontend of passage 59. Passage 59 is not necessarily in piston 55 but may belocated at any other suitable position.

A vent 61 is provided in the wall of the differential cylinder at thejunction of the sections of large and small diameters. This prevents airfrom being trapped in the cylinder underneath the larger diameterportion of piston 55.

Differential piston 55 can slide upon the valve rod 44 in order topermit relative movement between these two members under certainconditions; and disengageable connecting means are provided to connectthe piston to valve rod 44 so that under certain other circumstances thetwo parts move together as a unit. For this purpose, on a forwardlyprojecting portion of the differential piston there is mounted aplurality of housings 62 which are threaded into the projection of thepiston, these housings 62 each being held in place by a locknut 63, asshown particularly in Fig. 11. Within each housing is a compressionspring 64 which presses a ball 65 against valve rod 44. The valve rod isprovided with a circumferential groove 44a and when balls 65 are pressedinto this groove the piston and valve rod are connected together to moveas a unit. It will be realized that other types of releasable clutchmeans may be utilized for connecting the valve to the shifting member. I

Time delay detent means are provided to engage and hold the differentialpiston against premature movement when the piston is in the rearward orrest position shown in Fig. 6. This detent means is an apparatus of thedashpot type contained in an insert 66 in a vertically extending bore inblock 56.

In the bottom portion of the insert is plunger 67 which is providedatits lower end with a projection engageable with annular groove 168around the circumference of the differential piston. When the plungerengages this groove as shown in Fig.6, piston 55 is in engagement withthe forward end wall of the cylinder, passage 52 is not completelyclosed off by the piston (see Fig. 7).

Except for certain novel features of construction of adapter 4, theapparaus thus far described is generally old and is disclosed in theaforementioned'Patent No. 2,619,938. I have combined with this fluidmotor, apparatus of novel design for automatically initiating action ofthe fluid motor of any individual tuyre whenthe rate of flow of blowingair through the tuyre falls below a predetermined value as measured bythe rate of flow in the supply line for that tuyre.

'One element of the automatic control device is a valve shifting memberadapted to effect automatically the movement of valve 40 to theadmission position. This shifting member is here shown in the form ofdifferential piston 55 which is mounted to reciprocate within a differisheld against forward movement. Plunger 67 is normally biased towards thedownward position of engagement with the differential piston by spring68 contained within a bore insidethe plunger. One end of spring 68presses against the plunger while the other seats against a shoulder ininsert 66. Just above this shoulder, is an orificescrew 69 having alongitudinally extending metering orifice. The space below the orificescrew and above plunger 67 is filled with oil which can be forcedthrough the orifice in screw 69 into reservoir space 70 above. Access toreservoir 70 for replenishing or changing the liquid or for otherpurposesis afforded by removing screw plug 71. Plug 71 has a vent 71athrough which any excess pressure in reservoir 70 can bleed off to theatmosphere to prevent accumulation of super-atmospheric pressure in thereservoir that would affect the operation of plunger 67. The upper endof passage 71a is preferably covered by a porous filter to excludeforeign matter. 1

The lower end of plunger 67 is always exposed to the pressure of workingfluid in cylinder 57; and this fluid pressure exerts a force on theplunger which raises the plunger in opposition to spring 68. The upwardforce is greater than the downward force on the plunger when the fluidpressure in cylinder 57 reaches a predetermined value; After thispressure has been reached, plunger 67 rises; but its movement is delayedsince the oil below screw 69 must be forced upwardly through the orificetherein into reservoir 70 before the plunger rises Sllfi'. ciently todisengage the differential piston.

In order to prevent plunger 67 from being forced too far down bythe-action of biasing spring 68 when the differential piston is not inposition to limit downward movement of the plunger, limiting pin 72 isprovided as shown in Fig. 8. Pin 72 is threaded into the side ofcylinder block 56 and has a portion which projects into a shortvertically extending slot 73 in the side of the plunger. At the upperend of this slot is a shoulder which engages pin 72 in order to limitdownward range of travel of the plunger.

The release of fluid pressure in chamber 58 ahead of the diflerentialpiston is through exhaust passage means at the forward side of thedifferential piston; and fluid flow through the passage means iscontrolled by an exhaust valve assembly which includes a poppet-typevalve 75 which closes against a conical seat at 76 on insert 77contained in a bore in block 56. The details of this construction areshown particularly in Figs. and 13, the valve being shown in the openposition in the first of these figures. In the lower part of insert 77,the stem of valve passes through a bore of substantially larger diameterso that when the valve is spaced from its seat fluid in cylinder 58 canenter into this bore and then into laterally extending passages 78 inthe insert. These passages communicate with openings 79 in the cylinderblock which lead to the surrounding atmosphere. To eliminate the needfor exact alignment of passages 78 and 79, the block is counterbored at80 to provide an annular manifold passage between the valve insert andthe cylinder block which connects all of passages 78 with the terminalpassages 79.

The stem of valve 75 extends upwardly through a horizontal wall insert77 and at its upper end is provided with piston 81 movable withincylinder 82 formed in the upper end of insert 77. Between the bottomwall of the cylinder and the under side of piston 81 is spring. 83 whichnormally urges the valve upwardly to the raised or closed position ofFig. 13. When closed the valve is also held in that position by pressureof the fluid in cylinder 58 against the head of the valve. In order toopen valve 75 against this fluid pressure, piston 81 has a greater areathan the area on valve 75 exposed to pressure within cylinder 58. Also,the space under piston 81 is in free communication with the atmospherethrough passage 84 (see Fig. 13) which relieves pressure underneath thepiston that would interfere with down ward movement of piston 81 to openposition. The upper end of cylinder 82 is closed by plate 85 to retainfluid pressure within the cylinder. Thus valve 75 and its piston 81constitute a differential piston which can be moved to a position inwhich the valve is open by applying fluid pressure to the larger pistonend of the valve, as will now be explained.

Fluid under pressure is admitted into cylinder 82 from cylinder 58through a devious combination of passages. From cylinder 58, passage 87leads into the bottom of bore 88 in the valve block. In bore 88 is valveinsert 89 which has a centrally located passage 90 through which fluidgoes into the interior of the valve insert and then outwardly throughradial passages 91 into annular passage 92. This last passage isconnected by inclined passage 93 with cylinder 82.

The flow of fluid under pressure from cylinder 58 into cylinder 82through the system of passages just described is controlled by pilotvalve 95 which is mounted for vertical reciprocation in a bore insideinsert 89. When in the raised position of Fig. 10, fluid flow throughthese passages is permitted since passage 90 and radial passages 91 areuncovered by valve 95. When the valve is lowered as in Figs. '6 and 11,the valve closes central passage 90 and covers the inner ends of theradial passages 91 thus preventing any flow of fluid out of cylinder 58.This pilot type of valve structure 95 is selected because passage 90 isof such small diameter that but very little force is required to beexerted upon the valve by the diaphragm to keep it seated against theupper end of passage 90 in opposition to air pressure of the magnitudeencountered in cylinder 58, whereas forces of considerable magnitude maybe required at times to open or close exhaust valve 75. This way theexhaust valve is opened by the application of air pressure rather thanby a direct mechanical connection to the pressure responsive means, nowto be described, for operating the exhaust valve, the application of theair pressure being controlled by pilot valve 95 and the pressuresensitive elements.

In order to raise and lower pilot valve 95, it is connected. to thelower end of rod 96 which passes through and is connected toflexiblediaphragm 98. As will be explained more fully, this diaphragm is movablein response to fluid pressures applied to it; and a piston or other typeof movable member could. be used instead, but a diaphragm is preferredfor practical reasons as it can be made more sensitive to pressuredifferentials of small magnitude. Diaphragm 98 is confined around itsperiphery by having its marginal portions clamped between opposingshoulders on the two halves of cylinder block 56. Thus the diaphragmsubdivides an internal chamber into an upper chamber 99 and a lowerchamber 100. Diaphragm. 98 is preferably mounted between a pair ofreinforcing members 101 which are relatively rigid. The upper member 101engages the cylinder block at the top of chamber 99 to limit the upwardtravel of the diaphragm.

Rod 96 extends upwardly from the diaphragmv and passes loosely through aguide bore at 102 in a web of the cylinder block. A pair of lock nuts103 on the upper end of rod 96 provides a shoulder against whichcompression spring 104 bears, the spring surrounding rod 96 and bearingagainst the block around bore 102.

The upper ends of valve rod 96 and spring 104 are housed in sleeve 105threaded into the upper portion 56a of the cylinder block. Sleeve 105has an internal bore which extends the full length of the sleeve andwhich is closed by a manually operable valve assembly consisting ofvalve member 106 connected to cap 107 and compression spring. 108 heldbetween cap 107 and the top side of valve seat 109. Valve 106 engagesthe underside of seat 109 to provide a fluid-tight seal and prevent theescape to the atmosphere of any fluid under pressure in chamber 99 andis biased toward this closed position by spring 108. However, whenpressure is manually applied to cap 107, spring 108 is compressed andvalve 106 is lowered to open position in which fluid in chamber 99 canescape through bore 102 and around valve 106 to the atmosphere. For thisreason, the internal bore of cap 107 is larger than the externaldiameter of the upper end of sleeve 105. Upon release of manualpressure, the valve is closed by spring 108.

Diaphragm 98 is a pressure sensitive element whose position isdetermined at any time by the relative fluid pressures existing in upperand lower chambers 99 and 100 respectively. It is desired that theposition of the diaphragm be made to respond to fluid pressures existingat some location outside of the automatic control device, in thisinstance the location being in the air supply line to the tuyere withwhich the automatic control device is associated. For this purpose, themeans for supplying blowing air to the tuyere is provided with a flowmeter of the type creating a differential pressure having a knownrelation to the velocity of air flow within the air supply line. Asimple and convenient construction is to form a section of the airsupply means in the shape or with the characteristics of a Venturi tube.Equivalent means such as a Pitot tube or orifice meter may be usedinstead. Obviously this Venturi tube section may be located at anotherconvenient position, but it has been found convenient to form it withinadapter 4 as a part of internal cavity 6. Hence adapter 4 is designed sothat the blowing air after entering from conduit 14 passes through theconstricted throat 110 of the Venturi tube and then into the eglargedportion of chamber 6 before entering tuyere pipe The spaces above andbelow diaphragm 98 are placed in communication with the air stream atthe Venturi tube by means of two separate sets of passages. These areshown in Figs. 6 and 12. From lower chamber 100 passage 112 extendsforwardly through valve block 56 to a larger passage 113 in valve block114. Valve block 114 is fastened to adapter 4 by bolt 111. The forwardend of passage 113 is connected to throat 110 of the venturi by way ofpassage 115 in adapter 4.

By a similar arrangement passage 116 extends from upper space 99forwardly to passage 117 in valve block 114. From passage 117communication is through passage 118 to a point within the adapterupstream from the Venturi throat where the cross section of the airsupply passage is approximately the same as the cross section withinconduit 14. Thus the static pressure existing in the stream of blowingair at any time is communicated to space 99 above diaphragm 98. At thesame time the lower fluid pressure existing in Venturi throat 110 byvirtue of the increased stream velocity brought about by the decreasedcross section of the air passage at the throat, is communicated tochamber 100 beneath diaphragm 98. Hence, the position of the diaphragmis determined by the differential of fluid pressure existing at thesetwo points in the air supply line. 7

As will be further apparent from later discussion, the diaphragm, thepilot valve, and the exhaust valve constitute pressure responsive meansfor regulating air flow out of the forward cylinder 58 through theexhaust passages closed by valve 75. Because of the types of valves usedand the magnitudes of the pressures regulated as well as the regulatingpressures on the diaphragm it is preferred to control the exhaust valveindirectly, as through a pilot valve or other actuating means.

In each of bores 113 and 117 there is a valve 120 which is normallyurged by compression spring 121 toward a position in which the valveseats against an internal shoulder 114a in valve block 114 to close theassociated passage against the escape of air from the air supply line.When the fluid motor F and its control device G are mounted in place onthe tuyere, cylinder block 56 engages the ends of valves 120 and pressesthem inwardly to the position shown in Fig. 12 in which the valves openpassages 113 and 117. As long as the control device is in place thesevalves remain open and the communication between the control device andthe air supply line is maintained; and when the control device isremoved from the tuyere, bores 113 and 117 are automatically closed toprevent escape of blowing air from the system.

Manually operable means is also provided to release fluid pressure incl1amber100 at the underside of diaphragm 98 similar to valve 106 andpushbutton 107 already described. Extending laterally from chamber 100is passage 124 in cylinder block 56. Passage 124 intersects an upwardlyextending passage 125 which terminates at its upper end at the bottom ofbore 126 in the upper half 56a of the cylinder block. Intobore 126 isscrewed sleeve 127 having an internal bore within which valve 128 ismounted. The lower end of valve 128 engages the underside of annularseat 129 in sleeve 127 and the valve is biased toward this closedposition by spring 130 mounted on the valve stem and bearing at itslower end against the shoulder on the upper side of valve seat 129. Onthe upper end of the stem of valve 128 is mounted cap 131 and the upperend of spring 130 bears against the under side of the cap to force thevalve upwardly. By manually applied downward pressure on cap 131, spring130 may be compressed and valve 128 moved downwardly away from the valveseat to permit the flow of fluid out around the valve in the open upperend of sleeve 127. For this reason, clearance is provided between thedepending rim of cap 131 and the upper end of sleeve 127.

It is also preferred to incorporate in this structure another featuredisclosed in the Patent No. 2,619,938 referred to above. This is theprovision of a third air supply system generally designated as backpressure. It consists of an air line 134 connected to some relativelyfixed part of each'individual installation, as adapter cover plate 32,all lines 134 receiving air from manifold pipe 133 as shown in Figs. 1and 2. Air from line 134 goes through passage 135 in adapter plate 32into valve housing 136 (see Fig. 14) and thence out through the frontend of the valve housing and passage 137 into cylinder 48. Withinhousing 136 is valve 138 normally urged by spring 139 to a closedposition; When front cylinder head 22 engages the projecting end ofvalve 138 as the fluid motor is-mounted on the tuyere, the valve ismoved to the open position shown' in- Fig. 6 and air may flow throughthe passages into cylinder 48. However, when the fluid motor is removed,valve 138 is moved to a closed position by its spring and automaticallyshuts off the back pressure air supply so that air does not escape tothe atmosphere from line 134. This additional air supply is furnished inorder to maintain the body of fluid which is trapped in frontof workingpiston 26 at proper volume and pressure in order to insure full movementof the piston on its return stroke, as will be more fully described.Also, make-up air is furnished to allow for any loss through seepagepast either piston 26 or 47. The air or other compressible fluidsupplied through line 134 is at a relatively low pressure, say lbs. to 7lbs. per square inch above atmospheric. This is adequate to insure thenecessary body; of com pressible fluid at all times incylinder 20 aheadof working piston 26. Y Y

Another optional feature which is preferably provided in order to checkthe performance of the automatic control device, is pressure gauge 140.The pressure gauge is connected by means of an upwardly extendingpassage 141 with the cylinder space 58 ahead of the differential pistonand by indicating the fluid pressure existing in this cylinder thepressure gauge readings are evidence of gelrieral operating conditions,as will be explained more Having described the construction of myinvention,

I shall now set forth in greater detail the operation of my improvedform of automatic control device and how it initiates operation of thefluid motor for reciprocating the punch rod. When the fluid motor F andthe control device G are assembled on the tuyere and before operatingfluid is applied to the motor, the various parts may be assumed to be inthe positions shown in Fig. 6 which are referred to as the normal orrest positions of the several operating parts. Working piston 26 isfully retracted to the rear end of its cylinder. Differential piston 55is connected to valve rod 44 and both are at the rear of their strokes.The differential piston is held in place by plunger 67. When theassembled'fluid motor and its automatic control device are mounted onadapter 4, connections are automatically made with passages 113 and 117and the bore in housing 136 as the valves at these locations areautomatically opened. Operating fluid, such as compressed air or otherelastic fluid, is supplied to the motor and to the control devicethrough conduit 16 which is now connected to supply chamber 37. Astypical of the pressures used, but not necessarily limitative thereof,operating fluid is supplied at a pressure in the neighborhood of 75 lbs.to lbs. per square inch with the latter pressure preferred. Compressedair under this high pressure fills supply chamber 37 and cylinder 57,the latter being an extension of the former, and exerts a forwardpressure on the end of differential piston 55. Since initially there isno opposing pressure on the other end of the piston in cylinder 58, thepiston wouldmove forward if it were not locked in place by detentplunger 67.

High pressure air in rear cylinder 57 flows through passage 59 intoforward cylinder 58 at a rate which is determined by the size of theorifice in screw 60; and after the lapse of suflicient time the forwardcylinder is completely filled withair at a pressure which is equal tothe operating pressure in the rear cylinder and supply chamber 37. Whenthis condition exists the pressure rearwardly on the differential pistonis greater than the forward pressure because of the larger area exposedto the air pressure in cylinder 58. During this time the lower end ofplunger 67 has been exposed to the high pressure in cylinder 57 and theforce on the plunger exerted by the compressed air moves the plungerupwardly, compressing spring 68 and forcing liquid out of the spaceimmediately above the plunger through the orifice in screw 69 intoreservoir 70. The orifice in screw 69 is of a selected size to meter theflow of liquid to a desired rate. In this way the time required to liftdetent plunger 67 to disengage groove 168 in the differential piston issufficient that the air pressure in the forward cylinder 58 builds up toa pressure adequate to prevent forward movement of the piston.

Since the detent 67 is responsive to the pressure existing at one sideof the differential piston, its operation is automatic. Being of adash-pot construction it has a delayed action that prevents prematurerelease of piston 55. Forward motion of the piston is thus delayed untilthe normal desired fluid pressure is built up in the forward cylinder sothat the forward end of the piston is subjected to fluid pressureadequate to hold it in the rest position without the operation of detentplunger 67. This action is of value when the assembly consisting of afluid motor and its control device is first mounted on the tuyere aswhen a unit is being replaced that has been removed for servicing.Furthermore, by controlling the strength of spring 68 the detent can beprevented from disengaging the difierential piston when the operatingair pressure in the supply chamber falls below a predetermirliledminimum value, as for example 75 lbs. per square 111C t Followinginitial assembly, air also enters through passage 137 from' the backpressure line 134 which supassignm- 11 tively with compressed air atthis low pressure, though the invention is not limited thereto.

When the various cylinders within the fluid motor and its attachedcontrol device have become charged with fluid under pressure andpressures are stabilized throughout, the device may be said to be cockedsince it is now ready for normal operation. All parts are still in thesame position as in Fig. 6, except that detent plunger 67 is raisedclear of the cylinder as shown in Fig. 7. The device will now operateautomatically in response to pressure conditions existing at the Venturitube through which blowing air is supplied to the tuyere pipe. Blowingair is normally supplied through conduit 14 to pipe 3 at a pressure ofapproximately 12 to 15 lbs. per square inch, although this pressure isin no way limitative upon the present invention. When the tuyere isunobstructed blowing air flows through it and Venturi throat 110 at aknown rate depending on the supply pressure; and as a result there is aknown differential between the pressures existing in Venturi throat 110and at a selected point upstream from the throat where the air passagehas its full normal cross-sectional area.

it will be understood without detailed explanation that as accretionsforms at the forward end of the tuyre the tuyere becomes artificiallyconstricted with the result that air flows through it at a lower ratethan normal. In consequence there is a decrease in the rate of air flowthrough the Venturi section and a new and lesser differential isestablished between the air pressures existing in the Venturi throat andat the same selected point upstream therefrom. The two points at whichthese measurements are taken are of course fixed and are the locationsat which passages 115 and 118 open into the Venturi tube. The controldevice is designed to operate the fluid motor when the diiferential inpressures existing between these two points drops to or below apredetermined value.

By means of passages 112, 113 and 115 the fluid pressure existing at theVenturi throat is also maintained in space 100 beneath the diaphragm'98;while by means of passages 116, 117 and 118 the higher pressure existingupstream from the Venturi throat is applied to space 99 above thediaphragm. Under normal flow conditions the differential in pressure issufficient and in a direction to deflect diaphragm 98 downwardly untilvalve 95 closes ports 90 and 91, thus preventing escape offluidunderpressure from cylinder 58 ahead of the differential piston.Downward movement of diaphragm 98 compresses spring 104. When the rateof fluid flow through the Venturi throat drops below the minimumestablished for satisfactory converter operation, the differential fluidpressure on diaphragm 98 is reduced to a predetermined value. At orbelow this predetermined value, the upward force of spring 104 overcomesthe net downward force on the diaphragm as a result of the fluidpressures applied there to and spring 104 lifts the diaphragm upwardly,carrying valve 95 upwardly to the position of Fig. 10 in which airpassages 90 and 91 are open.

With these latter passages open, compressed air can escape from cylinder58 through passages 87, 90, 91, 92 and 93 into cylinder 82. In thiscylinder the fluid pressure builds up rapidly until piston 81 is drivendownwardly, as shown in Fig. 10, compressing spring 83 and movingexhaust valve 75 to the open position. The quantity of air escaping fromcylinder 58 through these passages into the cylinder 82 is relativelysmall, since the volume of cylinder 82 is small compared with the volumeof cylinder 58. As a result there is no appreciable reduction in thevalue of the air pressure in cylinder 58 and cylinder 82 fills veryrapidly. With the opening of exhaust valve 75 an escape passage toatmosphere of comparatively large size is made available throughpassages 78, 80 and 79 to cause a sudden and substantial drop inpressure in cylinder 58.

This drop in pressure permits differential piston 55 to move forwardlyunder the force applied to it by the operating air pressure at the rearof the piston. As the piston moves forward it gains in velocity and theforward cylinder continues to exhaust through open valve 75 so that theforward motion of the piston is not hindered.

As the differential piston moves forward it carries with it rod 44 byvirtue of its connection thereto through balls 65 engagingcircumferential groove 44a of the rod. This moves valve 40 from theexhaust position of Fig. 6 to the admission position of Fig. 7 in whichinlet port 1 s uncovered by the valve. This establishes freecommunication between supply chamber 37 and cylinder 20.

Forward movement of valve rod 44 also moves piston 47 and piston rod 49by virtue of engagement of the latter with valve rod 44. This forwardmovement continues until piston 47 hits the front end wall of cylinder48 as in Fig. 7, thus stopping forward movement of rods 44 and 49. Theparts are preferably proportioned so that the differential cylinder alsoengages retainer 50.

The back pressure on the forward side of piston 26 is sufficient to keepthe working piston normally in a fully retracted position (as in Fig. 6)in which the piston covers inlet port 38. However, this does not preventadmission of working fluid into the cylinder since the piston has smallbut adequate clearance between it and the cylinder walls to allow highpressure fluid to pass from inlet port 38 around the piston to reach therear face of the piston and drive it forward. For this reason. packingas shown at 26a to effect a fluid-tight connection betwen the piston andcylinder walls is limited to the forward end of the piston at a positionwhich is always forward of inlet port 38. Two advantages are secured bykeeping the piston when at rest at the extreme rear end of the cylinder.In the first place, the piston always makes a full and uniform strokesince it is definitely positioned at the beginning of each workingstroke. In the second place, the partial constriction of port 38 causesfluid pressure behind the piston to build up more slowly than if thespace were at once fully opened to the port with the result that piston26 accelerates more gradually and more smoothly.

After slide valve 46 has been advanced to uncover at least a part ofport 38, the operation of the fluid motor F is initiated and itsoperation is then substantially as described in greater detail in thePatent No. 2,619,938 referred to above. Briefly stated, the pistonstarts to move with a fluid pressure of relatively nominal value,perhaps 5 to 7 lbs. per square inch, ahead of it and a relatively highworking pressure reaching perhaps to 109 lbs. per square inch behind it.This relatively greater force causes the piston to accelerate rapidly,reaching a maximum velocity at about midpoint of the forward stroke. Forabout the last 15% of the stroke, the piston decelerates rapidly becauseof the absorption of its kinetic energy by air trapped between thepiston and the forward end wall of the cylinder. The body of fluid aheadof the piston eventually absorbs all of its energy remaining after thepunch rod removes accretions in the tuyere and brings the piston to astop at the dotted position of Fig. 4, and then by expanding returns thepiston rapidly to the rear end of the cylinder. The energy of forwardmovement is sufficient to raise the pressure ahead of the piston toseveral hundred pounds per square inch, which pressure insures fullreturn of the piston.

This return action is permitted by virtue of the valve return meanswhich shifts the slide valve 40 to exhaust position at some point latein the forward stroke of the working piston, which is about the positionof the piston in Fig. 7. As the pressure of the fluid ahead of theworking piston builds up the same pressure is transmitted throughpassage 52 to piston 47, and a point is reached at which the pressureacting upon piston 47 becomes sufficient to force that piston rearwardlyin cylinder 48. Because of engagement of piston rod 49 with valve rod 44the rearward movement of the piston shifts the valve rearward to theexhaust position of Fig. 6. In so doing, rod 44 is disconnected fromdifferential piston 55 since the differential piston is held in itsforward position by the continued high operating pressure on its rearside. Thus the slide valve is returned alone to its initial position inwhich port 38 is connected through the. valve with exhaust port 41.

As piston 26 starts its return or rearward stroke under the relativelyhigher fluid pressure existing on its front face, working fluid isexhausted through port 41 at a rate which can be controlled bypositioning slide 39 so as to restrict more or less the net opening ofport 41, to the atmosphere. This rate of exhaust has an effect upon thepiston movement. The more the exhaust outlet is restricted, the greaterthe resistance to the piston during its return movement; and this may beutilized to slow down its rearward velocity. As the leading face of thepiston passes port 38, a small amount of fluid is trapped between it andthe rear cylinder head to provide a cushion pressure that rapidlydecelerates the piston. However, in actual operation the piston maystrike the end ofthe control device.

spasms wall-and this, combined with the elastic nature of the trappedair, causes the piston to rebound silghtly'beyond port 38. The pistonthus mzy bounce or oscillate before it comes to rest. The final restposition is at the end of the cylinder (as in Fig. 6) since the pressurebetween the piston and the rear end of the cylinder is reduced to zerowhile at the forward face of the piston there is always the residualback pressure which pushes the piston rearwardly in its cylinder. 1

-- Assuming that the punching stroke of rod 15 is suflicientto clean outthe accretions in the tuyere, normal flow conditions are reestablishedwhich in turn causes 'reestablishment of the normal pressuredifferential across diaphragm 98. As a result the diaphragm is again de--fiected downwardly by air pressures acting on it, valve 95 cuts Eescape of fluid under pressure from cylinder 58 through passage 87 andconsequently pressure can now build up in cylinder 58. Air underpressure continually flows through passage 59 into cylinder 58 butduring this time has notbuilt up any pressure in the chamber as long asexhaust valve 75 remains open In practice, the reduction-of pressure incylinder 58 to substantially atmospheric allows the air under highpressure to escape from cylinder 82, which air has caused exhaustvalve75 to open. In this way cylinder 82 is drained of air, permitting theexhaust valve to close and again retain pressure within cylinder 58 infront of the differential piston.

- With the restoration of high pressure in cylinder 58, the force on theforward face of piston 55 is greaterthan on the rear face and the pistonis again driven back to its rearward position shown in Fig. 6 when balls65 snap into groove 44a and again connect the piston to the valve.

The fluid motor and its control device are again-cocked and ready foranother stroke.

The sizes of the various air'passages are such that it may requireseveral seconds to ready the apparatus for another stroke. A normaloperating condition is indicated by a pressure gauge reading of 100pounds, or whatever the line pressure is in conduit 16, within aninterval of 10 to seconds depending on the size of the orifice in-screw60, following the forward stroke of the piston. If a much lower gaugereading is indicated, it is a warning to the operator that for somereason the device is not operating properly.

It is characteristic of this fluid motor that piston 26 -moves through asinglecomplete reciprocation forward and back for each opening of motorvalve 40, which is promptly closed and cannot again be opened for atleast several seconds even when everything is working properly. Severalfeatures contribute to this, such as the small size of the orifice inscrew 60, the disconnectable nature "of the connection of piston 55 tovalve rod 44, and others. "For this reason, the fluid motor is termed asingle-cycle motor to distinguish from one adapted to repeated cycles ortocontinuous application of operating pressures to piston 26.

A number of different reasons may cause malfunction For example, dirt myclog one of the small air passages or settle on a valve seat, andprevent the valve from properly closing. Under such conditions airpressure in cylinder 58 may not build up to the minimum operatingpressure, herein assumed to be 75 pounds per square inch.

It sometimes happens that the punch rod does not sufliciently clean outa tuyere.

This may be a result of excessive accretions in the tuyere but is morelikely a result of mechanical failure because .the tip of the punch rodis worn or broken or may perhaps have been melted ofi. Under thesecircumstances, the normal rate of air flow through the tuyere is notrefor one of the reasons enumerated, or some otherreason,

the punching unitis not operating properly. If the difli- :culty. is inthe. failure of the punch rod to enlarge the .tuyere sufiiciently, thismaybe ascertained quickly by .cocking and subsequently actuating thepunching unit by means of'the manual control buttons. I

differential piston.

The motor and control mechanism may be chocked manually by depressingbutton 131 which opens valve 128 and places the under side of diaphragm98 in com.- munication with the atmosphere. As a result the pressureunderneath the diaphragm is lowered and the air pressure above thediaphragm forces valve downwardly to a closed position. If the button isheld down until gauge shows a pressure equal to the pressure of line 16,then the operator knows that the differential piston has again beenconnected to the valve rod and the device is cocked ready to operate.Action of fluid motor F may now be initiated by releasing button 131since upon release the diaphragm is raised by spring 104 in the absenceof air pressure above the diaphragm sufficient to hold it down inposition to close valve 95.

The control device may be manually operated to initiate a stroke of theworking piston at any time under normal operating conditions by manuallydepressing button 107. When button 107 is depressed sufiiciently tounseat valve 106, the space above diaphragm 98 is vented to theatmosphere and the higher pressure beneath the diaphragm raises pilotvalve 95, initiating action of the fluid motor in the manner describedabove.

During such periods as the blowing air may be shut off so that there isno pressure above atmospheric in conduit 14 or adapter 4, thedevice maystill be operated manually by depressing button 107 as far as possible.When no differential air pressure is applied to the diaphragm it israised by spring 104 to the upper position of Fig. 10 in which pilotvalve 95 is open. As valve 106 moves down, it first engages the upperend of valve rod 96, and further downward movement of the button causesvalve 95 to move downwardly to a seated or closed position. The valve isheld in this position by maintaining manual pressure on button 107 untilline pressure, as indicated by gauge 140, has been built up in cylinder58 ahead of the When button 107 is now released, spring 104 raises thediaphragm and valve 95 with the result that action of the fluid motor isinitiated in the manner previously described.

From' the foregoing description it will be seen that various changes indetails and arrangement of parts will occur to persons skilled in theart without departing from the spirit and scope of my invention. In thecourse of k the description, various departures from the preferreddesign have been mentioned but it will be realized that these are nottheonly changes that may be made; and it is to be understood that I am notnecessarily limited to the exact details of the disclosure already made.Consequently, it is to be understood that the foregoingdisclosure isconsidered as being illustrative of, rather than limitative upon, theappended claims.

I claim:

1. The combination with a converter tuyere subject to accumulation ofobstructions during normal converter operat on, a punch rod reciprocablewithin the tuyre for perio dlcally removing such obstructions, and anair supply line connected to the tuyre for supplying blowing air thatflows past the zone of obstructions into the converter, of apparatus forautomatically reciprocating the punch rod when obstructions reduce airflow through the tuyere below a predetermined value, comprising: asingle cycle fluid motor operatively connected to the punch rod torec1proca-te the rod upon supply of operating fluid to said motor andhaving a valve movable from a normal rest position shutting off supplyof operating fluid to the motor to a second position admitting operatingfluid to the motor; a movable valve shifting member; means forsubjecting opposite sidesof said valve shifting member to fluidpressure;exhaust passage means at one side of the valve shifting member openingto the atmosphere for relieving fluid pressure at said one side toproduce movement of the valve shifting member; means connecting thevalve to the valve shifting member to move the valve to said secondposition in response to said movement of the valve shifting member;exhaust valve means normally closing said exhaust passage; fluidpressure responsive means for opening said exhaust valve; and passagemeans placing the pressure responsive means in communication with theblowing air supply line to actuate said pressure responsive means whenthe rate of flow in the tuyere past the obstructions drops below apredetermined value.

.2. The combination as in claim 1 in which the ,apparatus forreciprocating the punch rod also CO11 '1PI1SS a second fluid supply.line supplying operating .fluid to the motor and directly to the valveshifting member at the side of the shifting .member away from theexhaust :p-assagemeans; and constricted passage means communicating withthe spaces at each of the two sides of the valve shiftingmember-conducting operating fluid to said one side of the shiftingmember adjacent the exhaust means at a relatively slow rate.

.3. The combination as in claim 1 in which the fluid pressure responsivemeans for opening the exhaust valve includes means biasing the exhaustvalve toward a normally closed position; a piston connected to thevalve; fluid passage means leading from said one side :of the valveshifting member to one side of said valve piston to apply fluid pressureto the piston in a direction to open the exhaust valve; a pilot valvecontrolling fluid flow through the last named fluid passage means; and amovable :pressure sensitive element connected to the pilot valve andsensitive to fluid pressure in the blowing air supply line to hold thepilot valve normally in closed position and to move the pilot valve toopen position when the flow of blowing air drops below a predeterminedvalue.

4. The combination as in claim 3 that also includes manually operatedmeans for moving the pilot valve to closed position.

5. The combination as in claim 3 that also includes fluid passage meanscommunicating between one side of the pressure sensitive element and theatmosphere, and a valve normally closing the last mentioned fluidpassage and movable to open the passage to release fluid pressure actingon one side of the pressure sensitive element.

6. In combination with a converter tuyre and a blowing air supply lineleading to the tuyere, an apparatus for automatically punching saidtuyere comprising: a punch rod mounted for reciprocatory movement in thetuyere; a fluid motor for effecting a single, rapid reciprocation of thepunch rod upon supply of Operating fluid to said motor; a valve normallyheld in a rest position shutting ofl supply of operating fluid to saidmotor and movable to a second position to supply operating fluid to saidmotor; a cylinder; a differential piston reciprocable in said cylinder;means for subjecting the piston at the side of smaller area to arelatively constant operating fluid pressure; means for supplying fluidunder pressure to the opposite side of said piston to hold the piston ina normal rest position; exhaust passage means leading from said cylinderat said opposite side of the piston for releasing fluid from saidcylinder to reduce the pressure at said opposite side; means operativelyconnecting the piston to said valve to shift the valve from said restposition to said second position in response to such decrease inpressure at said opposite side of the differential piston; exhaust valvemeans normally closing said exhaust passage; and means communicatingwith said air supply line and responsive to variations in flow of fluidin said air supply line, operable to open said exhaust valve when therate of flow of fluid in said air supply line decreases below apredetermined value.

7. The combination as in claim 6 in which the apparatus for punching thetuyere also comprises: detent means biased toward a position ofengagement with the differential piston when in normal rest position,said detent means being subjected to the relatively constant pressure atthe smaller side of the differential piston to be held out of engagementwith the piston when said pressure exceeds a predetermined value; aconstricted passage through the piston conducting working fluid from theside of smaller area to the other side of a relatively slow rate; andtime delay means associated with the detent means to delay disengagementfrom the piston until fluid pressures at both sides of the diflerentialpiston are substantially equal.

8. In an automatic control device of the character described forcontrolling actuation of a single-cycle fluid motor having areciprocable valve shiftable between a normal rest position shutting offsupply of operating fluid to the motor and a second position admittingoperating fluid to the motor, the combination comprising: a cylinder; adifferential piston reciprocable insaid cyltinder; means for subjectingthe piston at the side of smaller area to a relatively constant workingfluid pres sure; a .constricted passage for supplying fluid underpressure at a relatively slow rate to the opposite side of said pistonto hold the piston in a normal rest position; detent means biased towarda position of engagement with the difierential piston when in saidnormal rest position, said detent means being subjected to therelatively constant fluid pressure at the smaller side of thedifferential piston to be held out of engagement with the piston when.said constant pressure exceeds a predetermined value; exhaust passagemeans leading from said cylinder at said opposite .side of the pistonfor releasing fluid from said cylinder to reduce the pressure at .saidopposite side; means operatively connecting the piston to said valve toshift the valve from said rest position to said second position inresponse to such decrease in pressure at said opposite side of thepiston; an exhaust valve normally closing said exhaust passage; andpressure responsive means connected to an air supplyline outside thecontrol device and responsive to variations in flow of fluid in saidline, operable to open said exhaust valve when the rate of flow of fluidin said air supply line decreases below a predetermined value.

9. An automatic control device as in claim 8 that also includestime-delay means associated with the detent means to delay disengagementfrom the piston for suflicient time that fluid pressures at both sidesof the difierential piston are substantially equal.

10. In an automatic control device of the character described forcontrolling actuation of a fluid motor having a valve shiftable betweenexhaust and admission positions, thecombination comprising: a movablevalve shifting member operatively connected to the motor valve; meansfor subjecting opposite sides of the valve shifting member to fluidpressure; exhaust passage means at one side of the valve shifting memberfor relieving fluid pressure at said one side; exhaust valve meansregulating fluid flow in the exhaust passage; a Venturi tube throughwhich a stream of air flows; pressure responsive valve operating meansopening said exhaust valve means in response to fluid pressure existingat said Venturi tube and comprising a second movable member, means forsubjecting one side of the second movable member to the fluid pressureexisting in the throat of the Venturi tube, and means for subjecting theopposite side of the second movable member to the fluid pressureexisting at a point upstream from the Venturi throat; and valve meansnormally biased to a closed position and manually operable to move to anopen position to release fluid pressure acting on one of the twoopposite sides of the second movable member.

11. In an automatic control device of the character described forcontrolling actuation of a fluid motor having a valve shiftable betweenexhaust and admission positions, the combination comprising: a movablevalve shifting member operatively connected to the motor valve; meansfor subjecting oppositesides of the valve shifting member to fluidpressure; exhaust passage means at one side of the valve shifting memberfor relieving fluid pressure at said one side; exhaust valve meansregulating fluid flow .in the exhaust passage; pressure responsive valveoperating means opening saidexhaust valve means in response :to'fluidpressure existing at a location outside the control device, and valvemeans normally biased toward a closed position and manually operable tomove to an open position to release fluidpressure acting upon saidpressure responsive valve operating means independently of pressuresexisting .at said location outside the control device.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 425,202 Blanchard Apr. 8, 1890 813,209 Holmes Feb. 20, 19061,257,369 Lower Feb. 26, 1919 1,423,786 Zoelly et a1. July 25, 19221,797,297 Ringle Mar. 24, 1931 1,907,538 Hanna May 9, 1933 1,980,349Neveu Nov. 13, 1934 2,020,847 'Miterefi Nov. 12, 1935 (Other references,on following page) Number UNITED STATES PATENTS Name Date Burke June 8,1937 OConner Aug. 9, 1938 5 Ganahl et a1. Nov. 28, 1939 Phillips June 3,1941 Doerner July 10, 1945 Number Number Name Date Larson et a1. Dec.23, 1947 Hunter Oct. 12, 1948 FOREIGN PATENTS Country Date Great BritainJune 18, 1943 Germany June 14, 1937

